1. Field of the Invention
The present invention relates to an image-receiving sheet for use in an electrophotographic process, and more particularly to a transparent film for use with an overhead projector (OHP), capable of producing high quality images thereon when image formation is carried out by an electrophotographic method, particularly by a multi-color electrophotographic method. The present invention also relates to an electrophotographic method using this image-receiving sheet.
2. Discussion of Background
At the image-fixing step in a series of electrophotographic processes, a toner image transferred to an image-receiving sheet is melted and deformed upon application of thermal energy from an image-fixing unit. The toner image deposited on the image-receiving sheet is thus firmly fixed thereon.
To smoothly and uniformly fix the melted toner image onto the image-receiving sheet, there is conventionally proposed a method of coating the surface of an image-receiving sheet with a resin layer with the same formulation as that of the resin for use in a toner employed.
To accomplish high quality image formation by the electrophotographic method, particularly by the multi-color electrophotographic method, it is necessary to impart high surface glossiness to the toner image formed on the image-receiving sheet or transparent film for the overhead projector (hereinafter referred to as the OHP film). For this purpose, toner particles by which a toner image is formed are required to be uniformly melted upon application of a sufficient amount of thermal energy thereto at the image fixing step.
Further, in the case of the OHP film, it is necessary to prevent light from being scattered at the boundaries of toner particles in the toner layer and being irregularly reflected at the surface of the toner layer in order to improve the color light transmission properties of the employed OHP film.
To perform the image fixing operation at a relatively low image-fixing temperature with the above-mentioned requirements taken into consideration, a resin for the toner having a low softening point is employed. As a result, a line image tends to become thick, and the sharpness and resolution of the obtained images are degraded as a whole. In addition, the hot off-set phenomenon and the spent carrier problem are readily induced.
On the contrary, when a resin having a high softening point is used for the toner, not only extremely high thermal energy is required to uniformly melt the toner particles, but also the image-receiving sheet and the OHP film are easily deformed because thermal energy is excessively applied thereto. In particular, thermal deformation of the OHP film becomes a serious problem.